U.S. Pat. No. 3,993,648 discloses a class of 2-nitromethylenetetrahydro-2H-1,3-thiazine compounds having useful pesticidal activity, 2-nitromethylene-tetrahydro-2H-1,3-thiazine having particularly high pesticidal activity. U.S. Pat. No. 4,052,388 discloses that the compound 3-acetyl-2-nitromethylene-tetrahydro-2H-1,3-thiazine also has useful pesticidal activity. However, all of those compounds have disadvantages which limit their practical use: all are unstable to light and heat, and are quite soluble in water, so that they can be relatively easily removed by dew or rain from a locus to which they have been applied.